This is a study of the musical and cultural interaction of the Mundas, an adivasi (tribal, aboriginal) group of east-central India, with Hindu caste communities living in the same region. Over the last three hundred years, Hindu and Muslim outsiders, whom Mundas call diku (alien, exploiter), moved into Mundari lands and gained dominance over Mundas and other adivasis. Although the Mundas consider the outsiders unwelcome intruders, they have borrowed their music and dances, segregating them into a communal song and dance repertory of the monsoon season called karam, from the Hindu karma. In this study, the karam complex of music, dance, and festivals is studied within its ethnographic, historical, and musical contexts and interpreted within the framework of the larger issue of tribal culture change in India.This study challenges the widely accepted assimilation models of tribal culture change, in which borrowings from Hindu castes are taken as evidence of gradual and inevitable Hinduization. Mundas have not simply borrowed the outsiders' music and dance, but redefined, restructured, recontextualized, and reinterpreted them to create a unique Mundari cultural expression, a musical buffer zone between them and the outside. This characteristically Mundari process of interaction with a foreign threat is also evident in other domains of their life (rituals, mythology, social organization, political movements). Transforming and internalizing the foreign has allowed them to participate in a regional culture and still preserve their distinct cultural identity and central values (communality, egalitarianism), despite centuries of disruptive change.India's tribal music cultures are largely unknown, not only outside India but also within. Their study has been dominated by collections of song texts and enumerations of genres, rather than analyses of musical sound structures, history, or cultural meaning. Anthropologists of India's tribal peoples have failed to recognize music and dance performance as outward expressions of deeper cultural processes. This study, based on an ethnomusicological approach that synthesizes the musical, textual, contextual, historical, and socio-cultural dimensions of music making, demonstrates the significance of music and dance performances as expressions of cultural identity in tribal India.